Amazon Aurora with PostgreSQL compatibility now supports cluster cache management, providing a faster path to full performance if there’s a failover. With cluster cache management, you designate a specific reader DB instance in your Aurora PostgreSQL cluster as the failover target. Cluster cache management keeps the data in the designated reader’s cache synchronized with the data in the read-write instance’s cache. If a failover occurs, the designated reader is promoted to be the new read-write instance, and workloads benefit immediately from the data in its cache.

Without cluster cache management, when a read-write instance fails over to a read-only instance and that instance is promoted to be the new read-write instance, the cache in the newly promoted instance doesn’t have the data that was “hot” in the failed instance’s cache right before it failed. This leads to degraded performance while the “hot” data is read into the new instance’s cache from storage.